1. Field of the Invention
An aqueous mixture of petroleum sulfonates is injected into a subterranean formation and displaced toward a production means to recover crude oil therethrough.
2. Description of the Prior Art
Aqueous petroleum sulfonate mixtures are effective to recover crude oil in primary, secondary, and tertiary recovery processes. For example, the mixture can be injected into an oil-bearing subterranean formation and displaced towards a production well to recover crude oil. Mobility buffer slugs, i.e. aqueous solutions containing mobility reducing agents, can be injected behind the mixture to improve oil recovery.
U.S. Pat. Nos. 3,254,714 and 3,275,075 to Gogarty et al, 3,497,006 to Jones et al and 3,506,070 to Jones teach processes using petroleum sulfonate in micellar dispersions.
The prior art teaches that the petroleum sulfonates desirably have an average equivalent weight within the range of 350 to 525. Other additives may be present in the aqueous petroleum sulfonate mixture to enhance oil recovery, e.g. hydrocarbon, cosurfactant, electrolyte, mobility reducing agent, viscosity reducing agent, etc.
Applicants have discovered a novel combination of petroleum sulfonates to obtain a more efficient oil recovery process.